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Adrenergic nervous system influences on the induction of ventricular tachycardia
Oscar A Pellizzón1, Juan S Beloscar, Enrique Mariani
1Arrhythmia Section, Cardiology Department, School of Medicine, National University of Rosario, Ocampo 1969, (2000) Rosario, Santa Fe 3100, Argentina. opelliz@fmedic.unr.edu.ar
Background:
Sudden cardiac death is a major cause of mortality in western countries and the ventricular tachyarrhythmias are mainly involved in this regard. The adrenergic autonomic nervous system has influences in provoking life-threatening arrhythmias, and the prevention of such arrhythmias with beta-blockers supports this viewpoint. To evaluate the effect of the adrenergic nervous system and some catecholamine-releasing stimuli on the induction of ventricular tachycardia, we decided to explore the occurrence of ventricular tachycardia in patients subjected to three consecutive tests, exercise testing, isoproterenol infusion, and mental stress.
Methods:
Nineteen subjects who experienced exercise test-induced ventricular tachycardia were subjected to an isoproterenol infusion and mental stress. All but one patient had cardiac disease, with 70% due to Chagas' disease. Seventeen of the 19 study subjects had normal ventricular function.
Results:
Exercise test-induced ventricular tachycardia was nonsustained in 17 patients and sustained in 2 cases. Isoproterenol infusion induced nonsustained ventricular tachycardia in 9 of 19 patients. Mental stress, on its own, was able to induce nonsustained ventricular tachycardia in 2 of 19 patients.
Conclusions:
Among patients preselected for exercise-induced ventricular tachycardia, almost half could be induced into ventricular tachycardia by isoproterenol infusion. Mental stress was a less powerful inducer of ventricular arrhythmias in this study group.